The present disclosure relates to a field of liquid crystal display, and more particularly relates to an alignment mark structure, a mask, a substrate and an alignment method for the mask and the substrate.
A flat panel display includes a variety of displays, such as a Liquid Crystal Display (LCD), an Organic Light-Emitting Diode (OLED) display, a Plasma Display Panel (PDP) display and an electronic ink display. OLED display is considered to be a third-generation display technology in the art following LCD display since it is thin, self-luminous and has many advantages of fast response, wide viewing angle, rich colors, high brightness, low power consumption, resistance to high temperature and low temperature, etc. OLED display may be widely used in smart phones, tablet computers, televisions and other end products.
However, the LCD display recently has a resolution up to 400 or more pixels/inch (pixels per inch, ppi), even with a future development trend of exceeding more than 500 ppi. To improve the display resolution, it may be necessary to accordingly reduce the pixel pattern, which raises a large challenge to the present OLED production technology. Because the existing mature OLED production technology employs orderly vapor deposition of red, green and blue organic light emitting materials on a substrate by use of a fine metal mask to prepare a color pixel pattern, the pixel pattern can be precisely deposited on a back plate only by precisely aligning the mask with the substrate firstly when the vapor deposition is performed.
At present, the alignment of the mask with the substrate cannot meet the requirements for directly vapor depositing pixel pattern. It is usually necessary to determine a deviation value between the mask and the substrate by an experimental vapor deposition, to set a compensation value according to the deviation value, and to readjust the mask, and then the vapor deposition can be carried out. Even it is so, it often occurs that the compensation value is incorrectly set or the precision of the device cannot achieve a desirable effect, which can easily cause damages and results in a complex production process of OLED display device and time consumption.